This invention relates to an apparatus for depositing a thin-film layer upon an optical or electric circuit element or magnetic substrate, and more particularly to improvements of such apparatus with respect to uniform film characteristics.
It is known to provide a vapor deposition apparatus capable of processing a number of batches of substrates continuously at one cycle of bell jar operation in a turret form, as, for example, disclosed in Japanese Utility Model No. Sho 38-25633 issued Nov. 27, 1963. In FIG. 1, a sectional view of this apparatus appears. The apparatus includes a vapor depositing chamber 1 mounted on the under surface of a round base and communicating the interior 2 of an enclosure 17, in the form of a bell jar, through an opening which is provided through the wall of the base. A shaft 6 which protrudes through the base at the center of the area thereof rotatably supports a turret 8 on which a number of batches of substrates 10 in carriers of dome shape 12 are situated to be coated. After the interior 2 and chamber 1 have been evacuated by a pump 14, each of the batches of substrates 10 is heated to a predetermined temperature by a respective radiant energy heater 18, then advanced one step ahead to lie above the vapor depositing chamber 1, and then an evaporant material is heated by a heater 4 to form an evaporant. After a thin-film layer has been applied on the surface of each of the substrates above the chamber 1, the turret 8 is rotated one step to process the next batch of substrates 10. The completion of coating of all the batches of substrates 10 is followed by a cooling step which is then followed by the opening of the bell jar 17 with the help of an oil hydraulic machine 19 to remove the batches of processed substrates 10 and replace them with a number of new batches of unprocessed substrates. Thus, the turret type vapor depositing apparatus has disadvantages of consuming a long time per one substrate to be processed and of making it difficult to control the properties of the applied thin-film layer produced in different cycles of bell jar operations due to the repeated evacuation and exposure to the ambient atmosphere of the vapor depositing chamber. To avoid these disadvantages, coating apparatus of the in-line type have been proposed in U.S. Pat. Nos. 3,568,632 and 3,656,454 to Cawthon and Schrader respectively in which a coating chamber, evacuated chamber, heating chamber, cooling chamber and vacuum tight chamber are positioned in line, and individually sealed by valve plates so that the chambers have respective atmospheres controlled independently of each other. This arrangement is, however, associated with an alternate disadvantage of increasing the size of the apparatus.
The present invention concerns an apparatus for vacuum deposition of thin-film layers onto the surface of an optical or electric circuit element or magnetic substrate.
A first object of the invention is to provide an apparatus of the character described which avoids or is less vulnerable to the foregoing drawbacks and which requires no larger area of installation than is necessary in the conventional apparatus.
A second object of the invention is to provide an apparatus of the character described capable of continuously processing of batches of substrates through pre-heating, vapor depositing and cooling chambers with little possibility of impurities entering these chambers from the ambient atmosphere.
A third object of the invention is to provide an apparatus of the character described in which the production of uniform film characteristics in the deposited layers on the substrates is assured.
A fourth object of the invention is to provide a novel evaporant material feeding mechanism assisting in further improvement of the uniformity of film characteristics.
These and other objects, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.